The present invention relates to a jet engine, and more particularly to a jet engine having an air net selectively created to prevent inhalation of objects to prevent FOD (Foreign Object Damage).
The dangerous situation of any aircraft, both commercial and military, is during approaching and leaving a runway of an airport. During the approaching toward and leaving away from the airport, the attitude of the aircraft is such that engines may easily inhale foreign objects thereby damaging the turbine engine. This is generally referred to as Foreign Object Damage, FOD.
The FOD is generally resulted by inhaling birds and debris on the runway. Once the turbine inhaled a foreign object, blades on the turbine will consequently be damaged more or less under the impact imposed by the foreign object. In a minor FOD, the engine may simply reduce it output thrust, while in a severe situation, the aircraft is forced to take an emergency landing or even crash immediately, especially for a combat airplane. However, when we check those foreign objects, it can be easily categorized into 1) metal, 2) gravels; and 3) others, including wood, ice cube and birds. If we further categorize those foreign objects by 1) preventable; and 2) unavoidable, then the preventable foreign objects are 1) debris of the guiding lamp on the runway; 2) soils introduced by vehicles; 3) broken parts from the airplane, such as nut, bolt, washer, screws, tube etc; 4) debris of rubber wheel; 5) gravels, rugs, plastic scattered on the runway; 6) tars, cement and other construction material; and 7) badges of personnel. The above mentioned foreign objects can be carefully prevented by cleaning the runway and/or working area frequently. In addition, by strictly requesting the personnel follow the operational procedures, those foreign objects can be carefully removed from the runway thereby prevent the FOD happened to the airplane during landing and takeoff.
The unavoidable foreign objects include birds, squirrel, rat and rabbits inhabited around the runway. Among those animals, the birds, generally referred to as xe2x80x9cbirds strikexe2x80x9d, are most unpredictable and difficult to prevent.
In order to prevent the airplane from being hit by birds, many measurements have been taken, which can be divided into 1) eliminating physically or chemically; and 2) expelling. In term of the eliminating, shotgun and traps are widely used to eliminate the birds approaching the runway. The following chemicals are also commonly used to eliminate the approaching birds, such as Alpha Choralose, 3-chloro-p-toluidin hydro-chloride, and fenthion. In view of the expelling, gas canyon, fireworks, forged eagles and tanned eagles are all used to expel the birds approaching the runway. Sometimes, even remote controlled airplane model, and siren are also used to expel the approaching birds.
However, those above described precautions are costly and many labors have to be involved. In addition, many of the measurements can only be done during the daylight with excellent visions within the limited area, such as the area adjacent to the runway. By the way, the chemicals and noises used will create more or less the pollutions which offense the residence near the airport.
According to the statistics, the birds strike are generally happened under two thousand feet, especially under one hundred feet in which the airplane is approaching and departing to and from the runway. This is a critical condition to any airplane because the airplane will almost immediately crash if the engines are too damaged to provide enough thrust. Apparently, many of the measurements mentioned above cannot reach the area under two thousand feet. Once the airplane exceeds the attitude of two thousand feet, since no birds can fly to such limit, no bird strike will happen.
It is the object of this invention to provide a jet engine having an air net device located adjacent to an inlet thereof and selectively created an air net to prevent objects from being inhaled into the engine.
In order to achieve the objective set forth, a jet engine in accordance with the present invention comprises a housing having an inlet. An air net device is located adjacent to the inlet cowl so as to create an air net configured by compressed air streams for adequately blowing foreign objects from entering the inlet.
According to one aspect of the present invention, the compressed air streams of the air net are generated by the engine and which are selectively triggered by valves.